DESCRIPTION: (Applicant's Abstract) The goal of this proposal is to study in detail the biological properties of T cells specific for tumor-associated antigens (TAAs) that arise either de novo (Aim 1) or postvaccination (Aim 2) in patients with melanoma. Using powerful and novel tools such as peptide/MHC tetramers and 10-color FACS analysis, we will assess the expression of up to 45 surface and intracellular markers, cytokine expression, and functional status of TAA-specific T cells isolated directly from melanoma patients. We will also determine the gene expression profiles of such cells (Aim 3) to elucidate the molecular differences between functional and dysfunctional TAA-specific T cell populations. By correlating these data with the clinical state of the patient from which each population is isolated and the eventual clinical outcome, we hope to understand why TAA-specific T cells are protective in some patients but not in others. Lastly, we will dissect the factors which mediate T cell dysfunction in cancer by testing various individual and combinations of immunomodulatory agents to induce or reverse T cell dysfunction (Aim 4). Together, these data should lead to a better understanding of the biology of the T cell response to melanoma, and may lead to improvements in current cancer immunotherapy approaches.